It also slows down more as you move faster, which means astronauts (宇航员) someday may survive so long in space that they would return to an Earth of the distant future.
出自-2011年6月听力原文
柯林斯高阶英汉双解学习词典释义
N-COUNT
航天员;太空人;宇航员
An astronaut is a person who is trained for travelling in a spacecraft.